SAN JOSE, Calif.--Light-emitting diodes will become economically attractive as replacements for conventional lightbulbs in about two years, a shift that could pave the way for massive electricity conservation, according to a researcher.

Right now, consumers and businesses can buy a light-emitting diode, or LED, that provides about the same level of illumination as an energy-hogging conventional 60-watt lightbulb, Steven DenBaars, a professor of material science at the University of California Santa Barbara, said at the SEMI NanoForum, taking place here this week. A principal advantage of the LED: It lasts about 100,000 hours, far longer than the conventional filament bulb

Unfortunately, the LEDs that can perform this task cost about $60, he said. (Prices vary on the Internet.) But prices have been declining by 50 percent a year, so two years from now the same LED should cost around $20.

"At $20 the payback in energy occurs in about a year," DenBaars said. The rapid return on investment will occur in places such as stores and warehouses, where the light is on through much of the day. A year after that, LEDs will be even more economical for more places as costs continue to decline.

Approximately 22 percent of the electricity consumed in the United States goes toward lighting, according to the U.S. Department of Energy.

To make matters worse, traditional lightbulbs are incredibly inefficient. Only about 5 percent of the energy that goes into them turns into light. The majority gets dissipated as heat.

If 25 percent of the lightbulbs in the U.S. were converted to LEDs putting out 150 lumens per watt (higher than the commercial standard now), the U.S. as a whole could save $115 billion in utility costs, cumulatively, by 2025, said DenBaars, and it would alleviate the need to build 133 new coal-burning power stations.

In turn, carbon emissions in the atmosphere would go down by 258 million metric tons.

"Multiply that by three and you get the worldwide savings," he stated. DenBaars then showed a picture of the globe at night. The landmass of the U.S. could easily be picked out by nighttime lights.

"We shoot a lot of light into space that doesn't need to be there," he noted.

Rising prices of electricity, combined with the antiquated nature of lightbulb technology, has prompted several start-ups and large industrial concerns to get into lighting.

Fiberstars, for instance, has come up with a way to replace hot fluorescent tube lights with light-emitting optical fiber in freezer cases in grocery stores. Hewlett-Packard spinoff Lumileds is also producing LEDs for a variety of applications.

LED technology is improving as well. UCSB has created an experimental LED that can put out 117 lumens per watt, while a Japanese company has developed one that can put out 130 lumens per watt.

Getting LEDs to produce white light that is tolerable to humans has also greatly improved. Manufacturers can do it two ways. One is to package red, green and blue LEDs in a way that the combined light shines white to the human eye. The other way is to make blue LEDs and coat them with a phosphor--a luminescent substance commonly used on fluorescent lamps.